The proposed project is intended to provide a better understanding of the physiology and metabolism of L. pneumophila through determination of essential nutrient requirements, incorporation of radiolabeled compounds, oxygen uptake in the presence of specific substrates, cellular enzyme activities, and capabilities to survive periods of nutrient deprivation. Analysis of the nutrient requirements in a defined medium have shown that arginine, cysteine, isoleucine, leucine, methionine, serine, threonine, and valine were required for growth. A medium containing just these eight amino acids supported the growth of L. pneumophila only if further supplemented with glutamic acid. The inorganic ions magnesium, phosphate, and potassium were also required for growth in defined medium. Oxygen uptake studies indicated that serine, oxaloacetate, pyruvate, glutamate, tyrosine and threonine stimulated respiration of washed cells of this organism. Extracellular enzymes produced by all strains of L. pneumophila include protease, lipase, acid phosphatase, nuclease(s), alpha-amylase and beta-lactamase. No elastase, collagenase, phospholipase C, hyaluronidase, chondroitinase, neuraminidase or coagulase was detected. Starvation survival studies indicated that the greatest survival was achieved with a high cell density, at 25 degrees (or less) in a buffered solution at pH6.